Book Reviews

Book Review 1Book Title: The Physiology of ReproductionBook Authors: Editors-in-Chief: E. Knobil, & J.D. KneillRaven Press, 1988. 2633 pagesBook Review 2Book Title: Long-term Studies in Ecology: Approaches and AlternativesBook Author: Gene E. LikensSpringer-Verlag, New York, 1988. 214 pages, 27 figures. ISBN 3-540-96743-5.Book Review 3Book Title: Oceans of Life off Southern AfricaBook Authors: Edited by Andrew I.L. Payne & Robert J.M. Crawford and illustrated by Anthony P. van DalsenVlaeberg Publishers, Cape Town, 1989. 300 pp., numerous figures, tables and photographs.Book Review 4Book Title: Biotic Diversity in Southern Africa: Concepts and ConservationBook Author: Edited by B.J. HuntleyOxford University Press, Cape Town, 1989. 380 pages, hardback edition.Book Review 5Book Title: Ecosystems of the World 14B, Tropical Rain Forest Ecosystems: Biogeographical and Ecological StudiesBook Authors: Edited by H. Leith & M.J.A. WergerElsevier, 1989

Can life-history and defence traits predict the population dynamics and natural enemy responses of insect herbivores?

1. Life-history differences between herbivorous insects with eruptive and latent population dynamics are potentially useful for predicting population size variability. An association has also been demonstrated between herbivorous insect defence traits and the responses of various natural enemies. 2. Here predictions of population dynamics and natural enemy responses based on life-history and defence traits are tested using Gonometa postica Walker and G. rufobrunnea Aurivillius, two Southern Hemisphere Macrolepidoptera (Lasiocampidae) species. The temporal and spatial variation in pupal abundance and patterns of pupal parasitism and predation for both species are described and quantified for the first time. 3. Eleven sites were sampled over four generations across the region where both species have historically reached high population densities. Although there was evidence suggesting that population synchrony is driven by weather patterns, site-specific environmental differences contributed to the observed population variability. This study is the first to quantify the extent of population size variability of a species with an intermediate position on the eruptive – latent population dynamic gradient, where data on insect population dynamics is scarce. 4. Support for the life-history – population dynamic relationship was found, as intermediate population size variability for these species was observed. Larval and pupal defence traits, however, were poor and inconsistent predictors of mortality rate. Pupal cocoon structure differences, previously documented for these Gonometa species, may in fact explain the interspecific differences in natural enemy responses found. 5. Predicted population dynamics and natural enemy responses may, however, be overridden by ecological conditions. Nevertheless, life-history and defence traits provide a useful basis for predicting population dynamics of poorly studied species.Centre of Excellence for Invasion Biolog

Fine-scale abundance and distribution of wild silk moth pupae

Although several factors influence herbivore insect distributions at any particular scale, the most important determinants are likely to differ between species with different life histories. Identifying what these factors are and how they relate to life history forms an important component of understanding the population dynamics of species, and the habitat requirements necessary for their conservation. The pupal stage of two wild silk moth species, Gonometa postica Walker and G. rufobrunnea Aurivillius (Lepidoptera: Lasiocampidae), is the target of harvesting practices that are totally dependent on the availability of pupae from natural populations. Consequently, and partly due to poor knowledge of the species’ biology, there is substantial interest in the distribution of pupae among and within trees for both these species. It was investigated whether between- and within-tree pupal distributions in these two species are non-random, and if so, whether there are relationships between pupation site use and tree characteristics such as tree size, available pupation space and branch position. Between-tree patterns in pupal abundance were random in terms of absolute spatial position, but markedly nonrandom with respect to tree characteristics. The apparent G. postica pupae were aggregated on large larval host plants, whereas the cryptic G. rufobrunnea pupae were aggregated on non-host plants. These patterns reflect the life history differences of the two species. In contrast, at the within-tree scale, branch position, aspect and tree shape influenced pupation site choice similarly for both species. These patterns might be related to microclimate. Documenting between-tree and within-tree patterns in Gonometa pupal distributions is the first step towards explaining pupation site selection, as well as identifying possible evolutionarily selective factors in the species, and generating testable hypotheses from these.Centre of Excellence for Invasion Biolog

The occurrence and distribution of <i>Trox</i>(coleoptera, trogidae) in the Kruger National Park

Eleven species of Trox are recorded from the Kruger National Park, Republic of South Africa, and their distribution mapped. Six of these have a widespread distribution in the Ethiopian region. Elements of tropical northern (e.g. T. mutabilis Haat), eastern (e.g. T. unguicularis Haaf) and south west arid (e.g. T. zumpti Haaf) faunas in the Park are discussed. Trox radula damarinus Per. is re-established as a valid species on account of its distribution and the male genitalia

Fluctuations in Availability of Arthropods Correlated with Microchiropteran and Avian Predator Activities

Aerial arthropods were sampled by driving a standard transect along the riparian forest of the Luvuvhu River, South Africa, to assess hourly and seasonal variations in available biomass. Sampling, with an air-plankton net mounted on a vehicle, was conducted hourly over 48-hour periods during the fullest phase of the moon for each of eight months during 1986/87. Seasonal variation in availability of terrestrial arthropods was assessed by means of six pitfall traps set in the riparian forest. On a daily basis, the available biomass of aerial arthropods was found to increase markedly at and during the two hours following sunset, with a slight peak at or in the two hours preceding dawn. Highest monthly availability was found to correspond with the warm summer rainy season, with a marked increase after the first rains. The peak for terrestrial arthropods was found to occur later in the summer than for aerial arthropods. These patterns of arthropod availability correlate well with the daily activity rhythms and seasonal reproduc- tion of microchiropteran bats and their avian predators

Parasitoids of southern African wild silk moths (Lepidoptera)

[No abstract available]Articl

Parasitoids of southern African wild silk moths (Lepidoptera)

[No abstract available]Articl